Re: Corolla Rough Idle After Timing Belt Change

Does the car have an idle air control valve and if it does, have you checked
it out?

I would have to check the manual, it may have an equivalent (mind you
I've checked almost every sensor). But here's some more progress on
the issue...

After pulling and plugging back in every sensor and vacuum line, the
idle is virtually back to 100% normal. I refrain from saying
absolutely 100% only because there is only the slightest hint of a
vibration. But then again, I could be over reacting to normal
operations (I've grown very sensitive to vibrations the last few days!
;)

I am beginning to think that when I power washed the engine, I somehow
managed to get some moisture into an electrical connection. I'm not
going to brake out the Champaign just yet, but I feel like I can now
see the light at the end of this tunnel.

I also think resetting the computer helped as well.

All things aside, my Corolla is running as near perfect as can be.
There's the very slightest hint of vibration left (you can feel it in
the driver compartment) but I think that is because of the fairly
noisy exhaust leak at the exhaust manifold gasket.

Thank you very much RayO and toyomoho for your help. I'll give
another update once I replace the exhaust gasket. This has been a
very mind tingling experience, and I hope my detailed postings will
help someone else with a similar problem.

Tom



On Wed, 30 Aug 2006 20:28:31 -0500, "Ray O"
<rokigawaATtristarassociatesDOTcom> wrote:


"SlyckTom" <tom@xxxxxxxxx> wrote in message
news:jl4cf2td91rn8kij1aj8nor3mee8co9jet@xxxxxxxxxx
How low is low? What is idle RPM when the engine is cold and when it is
warmed up?

This is hard to tell, since I dont have an RPM gauge. But I can tell
you that it idles slightly better when warm than cold.

Are you talking about camshaft timing or ignition timing? Were the
camshaft
timing marke aligned perfectly AFTER reassembly? A poorly running engine
is a symptom of one of the camshafts off by a tooth.

I am talking about both the camshaft and ignition timing. And yes,
they were both aligned after reassembly. I would understand if it was
off by a tooth if the engine performace was terrible, but it is not
once I am out of idle. In fact once Im driving it runs better than
ever.


Yup, that seems to rule out a mis-timed camshaft.

Disconect the vacuum hose to the EGR valve and plug the disconnected
vacuum
hose with your finger and see if the condition clears up. If it does not,
re-connect the EGR.

No EGR valve on this model...

See if you can measure manifold vacuum. You should have above 16 in Hg at
idle.

Manifold vacuum is on the money.

But here is some progress that I have made:

I reset the computer, and the car idles somewhat better - not perfect
but not nearly as poor as before.

Also, and this may be the first real sign of progress, if I disconnect
the Throttle Position Sensor, the car idles perfectly.

Another point I should make...I gave the engine a good power washing
after the job, and in the process appear to have made an exhaust
manifold gasket leak worse (cleaned eons of oil reside out). I wonder
if the introduction of air towards the O2 sensor perhaps is throwing
something off?

Thank you again,

TOm


I doubt if the O2 sensor is causing the rough idle.

Does the car have an idle air control valve and if it does, have you checked
it out?

.

Relevant Pages

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